Fuel cells are devices that produce electricity by an electrochemical process without requiring fuel combustion. Hydrogen gas is typically electrochemically combined with oxygen gas to produce electricity. The only by-products of this process are water vapor and heat. As such, fuel cell-powered electric vehicles reduce emissions and the demand for conventional fossil fuels by eliminating the internal combustion engine or, in the case of hybrid electric vehicles, operating the engine at only certain times.
However, it has been discovered that temperature may play a role in determining the response of the fuel cell voltages during startup when both the anode and the cathode are exposed to air prior to startup. More particularly, it has been discovered that cold temperatures, and particularly sub-freezing temperatures, may contribute to undesirable delays in fuel cell vehicle startup.
Test data has indicated that the combination of electrical current during a Hydrogen starvation period and temperature during fuel cell freeze starts impact the time delay until the minimum cell voltage in the fuel cell is able to reach acceptable levels. Without being limited by theory, the present inventors suspect that growth of Platinum Oxides (Pt-Ox) on the anode catalyst within the fuel cell may inhibit the Hydrogen-Oxygen Reaction (HOR) taking place within the cell. This growth may even inhibit HOR after sufficient Hydrogen is present in the anode compartment and may therefore lead to undesirable delays during cold starts.
The present inventors have therefore determined that it would be desirable to provide methods and systems for enhancing fuel cell system startup, particularly in cold temperatures, that overcome one or more of the foregoing limitations and/or other limitations of the prior art.